One thing I used to do when I was ferrotyping prints was to wax the tin before I used it. A really good car wax worked for me but I wasn't worried about longevity of the prints. They came out with a really high gloss.
The pitting is usually from bits of trash between the print and the drum. Have you looked to see that the print has no particulates floating around with it in the wash?
Another thing is to be sure you have a solid bead of water between the print and drum as you load it. That will help make the gloss more even and also slow the drying a bit.
I've also seen print flattener solution that will help with the cracking. I think it was mainly glycerin and water.